CN115164803A - Method for rapidly calculating thickness of copper on PCB surface - Google Patents

Method for rapidly calculating thickness of copper on PCB surface Download PDF

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Publication number
CN115164803A
CN115164803A CN202210770365.7A CN202210770365A CN115164803A CN 115164803 A CN115164803 A CN 115164803A CN 202210770365 A CN202210770365 A CN 202210770365A CN 115164803 A CN115164803 A CN 115164803A
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copper thickness
copper
test
thickness
area
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刘孟豪
张晓敏
陈秋萍
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Gultech Suzhou Electronics Co ltd
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Gultech Suzhou Electronics Co ltd
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Priority to CN202210770365.7A priority Critical patent/CN115164803A/en
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B21/00—Measuring arrangements or details thereof, where the measuring technique is not covered by the other groups of this subclass, unspecified or not relevant
    • G01B21/02—Measuring arrangements or details thereof, where the measuring technique is not covered by the other groups of this subclass, unspecified or not relevant for measuring length, width, or thickness
    • G01B21/08—Measuring arrangements or details thereof, where the measuring technique is not covered by the other groups of this subclass, unspecified or not relevant for measuring length, width, or thickness for measuring thickness

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Length Measuring Devices With Unspecified Measuring Means (AREA)

Abstract

The invention provides a method for rapidly calculating the thickness of copper on a PCB surface, which comprises the following steps: manufacturing a test board covering the width of copper on the surface of a common PCB of a PCB manufacturer; and calculating corresponding qualitative curves representing the relationship between different copper thicknesses and PAD widths by using the surface copper thickness gauge, calculating the actual copper thickness of the PCB to be measured by using the input PAD width and the display value of the copper thickness gauge according to the plurality of qualitative curves, and recording the corresponding relationship between the display value of the PAD width and the copper thickness gauge and the actual copper thickness so as to obtain a corresponding simulation comparison table. According to the invention, only one standard sheet is needed, and an operator can quickly obtain the corresponding actual copper thickness by only searching the simulation comparison table, so that the production investment is reduced, and the measurement efficiency is improved.

Description

Method for rapidly calculating copper thickness of PCB surface
Technical Field
The invention relates to the field of PCB processing, in particular to a method for rapidly calculating the thickness of PCB surface copper.
Background
During the manufacturing process of the PCB, the thickness of the copper face is often measured during the processing such as electroplating, circuit etching, etc. At present, the method for measuring the thickness of the surface copper mainly comprises two methods: (1) slicing and measuring by using a microscope; and (2) using a surface copper thickness gauge based on the micro-resistance principle. Among them, the slicing method is a destructive method, time consuming and costly, and inconvenient for collecting data in a production site. The surface copper thickness gauge method is non-destructive and quick, four probes are arranged on a probe of the surface copper thickness gauge, the outer two probes are a constant current source, the inner two probes measure voltage difference, and the four probes simultaneously contact the surface of the copper to be measured during measurement to form a loop. The resistance R can be obtained from the formula R = V/I, and the copper thickness can be calculated from R = (ρ × L)/(W × H), where ρ is the density of copper.
Because the surface copper thickness gauge method utilizes the relation between the copper thickness and the cross-sectional area, different standard sheets are required to be selected for calibration when measuring the surface copper with different widths; however, 50-100 different material numbers are produced on the production line on average every day, the material numbers need to be frequently switched, and the widths of areas for the probes to measure are different, so that the calibration needs to be carried out by using various standard sheets with different widths to collect accurate copper thickness data, which not only greatly increases the cost, but also undoubtedly increases the production time by replacing different standard sheets.
Disclosure of Invention
In order to solve the problems, the invention provides a method for quickly calculating the thickness of copper on a PCB surface.
The main content of the invention comprises:
a method for rapidly calculating the copper thickness of a PCB surface comprises the steps of establishing corresponding simulation comparison tables for different copper thickness measuring instruments, wherein the simulation comparison tables are comparison relation tables of PAD width and display values of the copper thickness measuring instruments and the copper thickness; the step of creating the simulation comparison table comprises the following steps:
preparing at least two test boards, wherein each test board comprises a substrate and a test area formed on the upper surface of the substrate, and the lower surface of the substrate is coated with a copper foil layer; the test area comprises a plurality of test units, and each test unit comprises PADs which are sequentially arranged and have different widths;
and utilizing the test board to create qualitative curve equations under different copper thicknesses for different copper thickness measuring instruments, wherein the qualitative curve equations are expressed as follows:
Figure BDA0003723863350000011
wherein i represents a number of a certain copper thickness, y i A display value representing a copper thickness gauge, x represents the width of the PAD; (ii) a A. The i 、B i 、C i Is a constant;
according to the qualitative curve equation of the copper thickness measuring instrument, according to the input PAD width and the corresponding display value y of the copper thickness measuring instrument, calculating the corresponding copper thickness according to the following formula: h = H i -[(y i -y)/(y i -y j )×(h i -h j )]Wherein h is i Denotes the actual copper thickness, y, of the number i i An output of a qualitative curve of copper thickness number i corresponding to the width of the input PAD; h is j Actual copper thickness denoted j; y is j The output of a qualitative curve of the copper thickness with the number j corresponding to the width of the input PAD is represented;
and creating a comparison relation table of the PAD width and the display value of the copper thickness measuring instrument and the copper thickness according to the calculated copper thickness.
Preferably, the preparation of the test plate comprises the steps of: a substrate according to a set size; etching is performed according to the designed pattern of the test area while coating the bottom surface of the substrate with copper foil.
Preferably, the copper thickness of the test panel with the greatest thickness is greater than the copper thickness to be measured for production; the remaining one of the test boards had a copper thickness that was half the thickness of the test board having the greatest copper thickness.
Preferably, the test unit includes an upper test sub-area and a lower test sub-area, PADs with different widths are sequentially arranged in the upper test sub-area and the lower test sub-area, and the arrangement sequence of the PADs in the lower test sub-area is opposite to the sequence in the upper test sub-area.
Preferably, the method for obtaining the qualitative curve equation of the copper thickness of the test board under different copper thicknesses by using the test board according to different copper thickness measuring instruments comprises the following steps:
measuring the thickness of the PAD of each test unit by using a corresponding copper thickness measuring instrument, and recording a display value displayed by the measuring instrument;
randomly selecting a plurality of test units, carrying out slice measurement on PAD in the test units, and comparing a measured value with a display value to calibrate the copper thickness measuring instrument;
calculating the average value of the display values of PADs with the same specification in a single test unit, and taking the average value as the output of a qualitative curve;
obtaining each qualitative curve by using curve regression software; a. The i 、B i 、C i The best fit of (c).
The invention has the beneficial effects that: the invention provides a method for quickly calculating the copper thickness of a PCB surface, which comprises the steps of manufacturing a test board covering the copper width of the PCB surface which is common in PCB manufacturers, calculating corresponding qualitative curves representing the relation between different copper thicknesses and PAD widths by using a surface copper thickness meter, calculating the actual copper thickness of the PCB to be measured by using the input PAD width and the display value of the copper thickness meter according to the qualitative curves, recording the corresponding relation between the PAD width and the display value of the copper thickness meter and the actual copper thickness, and obtaining a corresponding simulation comparison table, so that only one standard sheet is needed, and the corresponding actual copper thickness can be quickly obtained by searching the simulation comparison table, thereby reducing the production investment and improving the measurement efficiency.
Detailed Description
The following is a detailed description of the technical solution protected by the present invention.
The invention discloses a method for quickly calculating the copper thickness of a PCB surface, which comprises the steps of establishing corresponding simulation comparison tables for different copper thickness measuring instruments, wherein the simulation comparison tables are comparison relation tables of the display values of PAD width and copper thickness measuring instruments and the copper thickness; when a worker measures the copper thickness, the worker calibrates the standard sheet, measures the PCB to be measured, only needs to input the PAD width of the PCB to be measured to obtain a display value on the corresponding copper thickness measuring instrument, and then searches the simulation comparison table to obtain the actual copper thickness.
Specifically, the creating step of the simulation comparison table comprises:
firstly, preparing at least two test plates with different copper thicknesses, wherein each test plate comprises a substrate and a test area formed on the upper surface of the substrate, and the lower surface of the substrate is coated with a copper foil layer; the test area comprises a plurality of test units, and each test unit comprises PADs which are sequentially arranged and have different widths.
Specifically, a copper foil with a certain thickness is coated on the upper surface of the test board, and then a plurality of test units which are sequentially arranged are formed by etching, wherein each test unit is rectangular; furthermore, a plurality of PADs with different widths are formed in the rectangular interior of each test unit in an etching mode, the width of the PADs is only required to be common, and for example, 8 PADs with the width of 2mm, 4mm, 6mm, 8mm, 10mm, 15mm, 20mm and 25mm can be included in a single test unit, the height of each PAD is the same, and the PADs are rectangular; furthermore, in order to avoid a forming error introduced in an etching process, a single test unit comprises an upper test sub-area and a lower test sub-area, PADs with different widths are sequentially arranged in the upper test sub-area and the lower test sub-area, and the arrangement sequence of the PADs in the lower test sub-area is opposite to that in the upper test sub-area; that is, when 8 PADs with widths of 2mm, 4mm, 6mm, 8mm, 10mm, 15mm, 20mm and 25mm are sequentially arranged in the upper test sub-area, the PADs are arranged in the lower test sub-area in the reverse order.
And utilizing the test board to establish a qualitative curve equation under different copper thicknesses of different copper thickness measuring instruments, wherein the qualitative curve equation is expressed as:
Figure BDA0003723863350000031
wherein i represents a number of a certain copper thickness, y represents a display value of the copper thickness measuring instrument, and x represents the width of PAD; a. The i 、B i 、C i Is a constant;
in this example, two test boards with different copper thicknesses can be prepared, such as a test board with a copper thickness of 64.28 μm, and the qualitative curve can be expressed as:
Figure BDA0003723863350000032
for a test board with a copper thickness of 30.6 μm, the qualitative curve can be expressed as:
Figure BDA0003723863350000033
then, a certain copper thickness measuring instrument is utilized to record the corresponding copper thickness of PAD with all the widths, namely the display value of the copper thickness measuring instrument, and the respective A can be obtained by means of the common curve regression software i 、B i 、C i The best fit of (c).
Further, measuring the thickness of the PAD of each test unit by using a corresponding copper thickness measuring instrument, and recording the display value of the measuring instrument; then randomly selecting a plurality of test units, carrying out slice measurement on PAD in the test units, and comparing a measured value with a display value to calibrate the copper thickness measuring instrument; in other embodiments, the actual thickness of the test board can also be determined by measuring the thickness of the grooves by making wider grooves between adjacent test cells.
Calculating the average value of the display values of PADs with the same specification in a single test unit, and taking the average value as the output of a qualitative curve, namely the display value of the copper thickness measuring instrument;
a was obtained for each qualitative curve using curve regression software i 、B i 、C i The best fit of (2).
Then, according to qualitative curve equations under different copper thicknesses, calculating the corresponding copper thickness for different PAD widths and the corresponding display value y of the copper thickness measuring instrument according to the following formula: h = H 2 -[(y 2 -y)/(y 2 -y 1 )×(h 2 -h 1 )]Wherein h is 1 Represents the copper thickness, y, corresponding to a qualitative curve with a copper thickness of 64.28. Mu.m 2 The output of the qualitative curve representing a copper thickness of 64.28 μm; h is 2 The copper thickness is expressed by a qualitative curve of 30.6 μm; y is 1 Represents the output of a qualitative curve with a copper thickness of 30.6 μm; and finally, creating a comparison relation table of the PAD width and the display value of the copper thickness measuring instrument and the copper thickness according to the calculated copper thickness.
The comparison relation table can be stored in a personal PC or a used application system in the form of an Excel table and the like, and when the PAD width of the PCB to be tested is different from the standard sheet, a user only needs to input the width of the PAD to be tested and the display value of the copper thickness measuring instrument to calculate the actual copper thickness of the PCB to be tested.
The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes, which are made by the present specification, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.

Claims (5)

1. A method for rapidly calculating the copper thickness of a PCB surface is characterized by comprising the steps of establishing corresponding simulation comparison tables for different copper thickness measuring instruments, wherein the simulation comparison tables are comparison relation tables of PAD width and display values of the copper thickness measuring instruments and the copper thickness; the step of creating the simulation comparison table comprises the following steps:
preparing at least two test boards, wherein each test board comprises a substrate and a test area formed on the upper surface of the substrate, and the lower surface of the substrate is coated with a copper foil layer; the test area comprises a plurality of test units, and each test unit comprises PADs which are arranged in sequence and have different widths;
utilizing the test board, aiming at different copper thickness measuring instruments, establishing qualitative curve equations under different copper thicknesses for the test board, wherein the qualitative curve equations are expressed as follows:
Figure FDA0003723863340000011
wherein i represents a number of a certain copper thickness, y i A display value representing a copper thickness gauge, x represents the width of the PAD; (ii) a A. The i 、B i 、C i Is a constant;
according to the qualitative curve equation of the copper thickness measuring instrument, according to the input PAD width and the corresponding display value y of the copper thickness measuring instrument, calculating the corresponding copper thickness according to the following formula: h = H i -[(y i -y)/(y i -y j )×(h i -h j )]Wherein h is i Denotes the actual copper thickness, y, of number i i An output of a qualitative curve of copper thickness number i corresponding to the width of the input PAD; h is j Actual copper thickness denoted j; y is j The output of a qualitative curve of the copper thickness with the number j corresponding to the width of the input PAD is represented;
and creating a comparison relation table of the PAD width and the display value of the copper thickness measuring instrument and the copper thickness according to the calculated copper thickness.
2. The method of claim 1, wherein the step of preparing the test board comprises the steps of: a substrate according to a set size; etching is performed according to the designed pattern of the test area while coating the bottom surface of the substrate with copper foil.
3. The method of claim 2, wherein the test board with the largest thickness of copper thickness has a copper thickness greater than the copper thickness to be measured for production; the copper thickness of one of the remaining test boards is half the thickness of the test board with the largest thickness of copper.
4. The method as claimed in claim 2, wherein the test unit comprises an upper test sub-area and a lower test sub-area, PADs with different widths are sequentially arranged in the upper test sub-area and the lower test sub-area, and the arrangement sequence of PADs in the lower test sub-area is opposite to that in the upper test sub-area.
5. The method for rapidly calculating the copper thickness of the PCB surface according to claim 1, wherein the qualitative curve equation under different copper thicknesses of the PCB surface is obtained by the test board aiming at different copper thickness measuring instruments, and the method comprises the following steps:
measuring the thickness of the PAD of each test unit by using a corresponding copper thickness measuring instrument, and recording a display value displayed by the measuring instrument;
randomly selecting a plurality of test units, carrying out slice measurement on PAD in the test units, and comparing a measured value with a display value to calibrate the copper thickness measuring instrument;
calculating the average value of the display values of PADs with the same specification in a single test unit, and taking the average value as the output of a qualitative curve;
obtaining each qualitative curve by using curve regression software; a. The i 、B i 、C i The best fit of (2).
CN202210770365.7A 2022-06-30 2022-06-30 Method for rapidly calculating thickness of copper on PCB surface Pending CN115164803A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202210770365.7A CN115164803A (en) 2022-06-30 2022-06-30 Method for rapidly calculating thickness of copper on PCB surface

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202210770365.7A CN115164803A (en) 2022-06-30 2022-06-30 Method for rapidly calculating thickness of copper on PCB surface

Publications (1)

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CN115164803A true CN115164803A (en) 2022-10-11

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